Tunable suppressor for filament feedback disturbances



Jan. 12, 1943. s. WHISK Y 2507 979 TUNABLE SUPPRESSOR FOR FILAMENTFEEDBACK DISTURBA NCES Fil ed om. e, 1941 ATTORNEY.

Patented Jan. 12, 1943 TUNABLE SUPPRESSOR FOR FILAMENT FEEDBACKDISTURBANCES Samuel Whisk, Brooklyn, N. Y., assigncr of onehalf toMorris Abrams and Morris Zippert, both of Brooklyn, N. Y., jointlyApplication October 6, 1941, Serial No. 413,744

1 Claim. (Cl. 250-27) This business relates to devices for suppressingdisturbances that originate in the filament circuits of radio tubes.

One object of the invention is to provide an improved semituned powerfilter adapted for suppression of disturbances by the conjoint action ofa choke coil and a condenser.

Another object of the invention is the provision of improved means forthe superior suppression structions. The accompanying drawing,therefore, is submitted merely as showing the preferred exemplificationof the invention.

Referring in detail to the drawing, in denotes a device embodying theinvention. The same may include any source I l of direct current,connected by a circuit l2, l3 to the filament M of a radio tube l5,which may comprise the conventional grid and plate It, I 1 respectively.Disposed in the of all local disturbances at diiferent frequencies,circuit l2, I3 between the power source and the especially with respectto the filament circuit of a output or tube I5 is a variable transformerI8, radio tube. comprising inductance coils I9 and 20. Different- Whilechokes and condensers have been used 1y stated, the circuit l2, l3comprises a choke coil for1i suppresslng fie? backd the pgwgar supply of1 g, the samte being arranged to 3constitutebimetIof 0 rflcelvers, laveISCOVETB .v 0 X- 5 e elemen s of transformer Desire. y e perimentationthat some disturbances are nevercoils I9, are wound in like direction.theless set up or fed back into the positive side or' In order toovercome varying disturbances in hot 6% 0f t c uit; others are generatedo the power circuit l2, it, at varying frequencies. fed back in thereturn or negative side of t e while maintaining the energy of thedesired curc So e O t ese distu a e a e e 20 rent, I provide meanscooperating with the choke ated 011 the Output -8 O the i u t; Ot ers oor transformer coils or both for grounding the gi p g ic-f th m f samethrough capacities at different endsTof the e 0 Jec o e invention is iere ore to prO- transformer coils as may be required. bus I videimproved means to overcome these defects. provide a like unit 2! at eachend of the transn again, I have discovered that the reducformer inparallel therewith. For example, a tion of disturbances whilemaintaining the desired lead 22 is connected across the circuit l2, 13,current did not occur with uniform efficiency this lead being centrallygrounded at 23. teach especially Where different eq en ies Were insideof the ground connection is disposed a convolved. denser, so that forthe two units 21, there are It is therefore another je t of theinvention provided condensers 24, 25, 2t and 21, all of which to p' p oed means for avoiding this difiimay be of like capacitance. By means ofswitches u y- 28 a connection to ground through capacitance Otherobjects and advantages of the invention may be made by closing any oneor more of the will become apparent as the specification proceeds. withes 28 in any desired combination.

With the afo esa d Obje s in V w, e i ve The device it utilizes thevarious capacitances tion Consists in t e ovel mb o s and and thevariability of the transformer for elimia a ements of parts here a tedescribed in hating disturbances at different high frequencies. theirprelferlred embgdil he ztatpointetdhout in th; By selective zgttigg dofthg translformer tand Sf subJ'Oine 0 a m, an i us ra ed in e annex theswitches ,t e esire signa curren i o drawin w er li p ts are designatedy the 40 tained free of extraneous frequencies. By the same referencecharacters throughout the several provision f plurality of it H, th c tl VieWS- as above indicated is exercised not only for supthe dr3jWing3pressing the feed back in the power supply of Flgure 1 d1aramm?'t1c ofan appa' radio receivers, but also disturbances generated m P m or fedback in the return or negative side of the 1S .Slmuar Vlew showmgmcdlficatlon circuit. All such disturbances will be eliminated 'l l lg dl rfi ges 0f the invention as here out- Whether gengraaqid g j 011m) 2%the lined are best realized when all of its features and side of theclrcul I 1 c device as een ioun instrumentalities are combined in oneand the particularly effective where the same relocated same structure,but, useful devices may be relatively close to the generators orignition coils duced embodying less than the whole or airplanes and oicomparatively small boats.

It will be obvious to those skilled in the art to B t e t the r f-"expensive which the invention appertains, that the same l dms 1 elim nd, Wi av e n metal, may b incorporated in several different c labor andwith increased compactness. When quency detector and the first audiofrequency 7 stage; this device 39 like that at It serves to eliminatedisturbances in'the power circuit and reduces undesired frequencieswhile permitting maintenance of desired current strength.

Accordingly there are shown the second detector tube 3! and the tube 32for the first audio stage, the plate 33 of the former beingconnected tothe grid 34 of the latter by a circuit 35 having therein a condenser 3%.Connected to the lead 35 is a circuit 3'! which comprises the condenser36 and also a variable transformer 38. The lat-- ter may include coil39, to, of which the former may be variably tapped as indicated at 4| toground, as by means of series resistances 42, 43, grounded at 64.Intermediate of these resistances is connected a condenser M which isgrounded at 15. Desirably the coil 463 may constitute the primary, andit is connected to resistances d7, :13 which are in series with a sourceof power t!) that is grounded at 59. Intermediate of the resistances 41,48 is connected a condenser di grounded at 52. The condensers 36, 45 andmay be of like capacitance, the same beingvchosen according to the powerin the circuit 35 as will be apparent to any one skilled in the cart.

Efficient operation is obtained by the combined efiects of the variabletapping at 4| and change of angle of a transformer coil to thus vary thephase; this result is rendered possible by the favorable conditionscreated by the 'balanced'. grounding through capacity resistances 42,

and 41, 48.

In the interpretation of the invention as claimed, the term resistivemeans may include v. condensers such as those in the devices Hi and Iclaim:

An apparatus includingla circuit having a por tion for connection to thefilament of a radio;

tube, atsource of current for the filament in said circuit, a choke coilin one line of the circuit, an inductance in the other line of thecircuit,

said chokecoil and inductance coil constituting a variable transformerlocated between the cur rent source and theicircuit portion for thefilament, the circuit having shunt branches one of which interconnectssaid lines at one end of the;

transformer and the other of which interconnects said lines :at theother end of the transformer,

each branch having individual like control means, each of the latterincluding a plurality of condensers, a ground connection therebetween,'a switch for each condenser located between its condenser and theground connection, whereby either or both condensers can be connected'tosaid ground connection or disconnected there-

